In recent years, with the spread of therapy using molecular target drugs based mainly on antibody drugs, quantitating a biological substance in cells of the observation target has been desired for more efficient design of the molecular target drugs. For confirming the presence of a specific biological substance, a method of tissue analysis is known on the basis of staining of cells using a fluorescent substance specifically bindable to the biological substance.
Patent Document 1 proposes a method of improving accuracy in quantitating the expression amount of biological substance by measuring the number of fluorescent bright spot in the tissue sample as follows: staining the tissue sample with a phosphor bindable to the biological substance, analyzing peaks in the luminance distribution of the fluorescent bright spot in the tissue sample, and calculating average luminance of one particle of the phosphor.